1) Field of the Invention
The present invention generally relates to a cross-connecting system, and more particularly to a cross-connecting system which connects a high-speed line and a low-speed line or two high-speed lines.
In recent years, in a communication field, flexibility and high efficiency have become a great concern for communication networks.
In order to achieve flexibility and high efficiency for communication networks, a conventional communication apparatus is provided with a cross-connecting function which can freely make a line connection between a high-speed line and a low-speed line or between two high-speed lines.
However, as a number of lines and a number of communication apparatuses provided in a network increase, an operation time for setting a line in each of the apparatuses increases. Accordingly, an installation time for the communication apparatus is increased due to a time spent on a detecting operation for a line-connection error.
In order to reduce the installation time, a function is required for the apparatus which can automatically detect a line-connection error.
2) Description of the Related Art
FIG. 1 is a block diagram of a conventional cross-connecting apparatus 11 and peripheral devices. The cross-connecting apparatus 11 is connected to a high-speed line 12 and a low-speed line 13. Between the high-speed line 12 and the cross-connecting apparatus 11, there are provided multiplexers (MUXs) 14 which multiplex a signal output from the cross-connecting apparatus 11 and demultiplexers (DMUXs) 15 which demultiplex a signal input from the high-speed line 12 and supplies the demultiplexed signal to the cross-connecting apparatus 11.
There are provided on a drop-side of the low-speed line 13 a path switch 16 and an identification (ID) information detecting unit 17. The path switch 16 switches a connection of the low-speed line 13 to either side of the high-speed line 12. Additionally, an identification (ID) information adding unit 18 is provided on an add-side of the low-speed line 13.
In the above-mentioned structure, identification (ID) information is added to signals on the low-speed line 13, and then the signals are sent to the multiplexer 14, via the cross-connecting apparatus 11. The identification information is arbitrarily set by an operator for checking whether or not a signal line routing from one cross connecting apparatus to a remote cross-connecting apparatus is correctly established. The identification information may be, for example, a character code by which a line can be identified.
The remote cross-connecting apparatus which received the identification information sends a main signal, input from the high-speed line 12 via the demultiplexer 15, to the low-speed line 13. The main signal is then sent to a desired line by means of the path switch 15, and the identification information included in the main signal is detected by the ID information detecting unit 17.
In the ID information detecting unit 17 of the remote cross-connecting apparatus, it is determined whether or not the identification information is included in an incoming main signal. When the identification information is detected by the remote cross-connecting apparatus, the detected identification information is compared with the identification information which must be detected by means of software. Then the operator checks a result of the comparison on a display. If the identification information is detected in an abnormal state, an operator must check a state of each connection in a network one by one so as to find a connection error.
As mentioned above, in the prior art, it is determined that the line connection is properly made only when identification information which has been sent by a cross-connection apparatus of a sending side is exactly detected by the ID information detecting unit of a receiving side. When the identification information is not detected or the received identification information is not proper identification information to be received, most of error seeking and correcting operations rely upon the judgment of the operator. Accordingly there is a problem in that a long time is spent on a set-up operation of lines, in particular, for a network having a complex construction.
Japanese Laid-Open Patent Applications No. 3-214949 and No. 5-1229 disclose a checking apparatus for checking a connection in a cross-connecting apparatus. In this checking apparatus, a main signal is input from an input of a cross-connecting apparatus so that the main signal is output from the cross-connecting apparatus. The checking apparatus checks a line connection within the cross-connecting apparatus by using an overhead provided in a frame of the main signal output from the cross-connection apparatus. This checking apparatus checks only a state of a line-connection from a view point of hardware. Accordingly, this checking apparatus is not capable of detecting a connection error in a network in which a plurality of cross-connecting apparatuses are provided, and thus an error seeking operation still relies upon a judgment made by an operator as previously mentioned.